Dispensers for dispensing a viscous or extrudable material have been proposed in a wide variety of designs, ranging from a common piston-type caulking gun found in any hardware store to small hand-held twisting devices for rolling up a tube of extrudable toothpaste. Dispensers for extrudable material even have been proposed for hydraulic actuation. Commonly, the extrudable material is dispensed from a cylindrical housing by an advancable piston. Other dispensers are designed for collapsible containers and employ roller mechanisms which take the place of the more common advancable piston. When used as hand implements, most such dispensers have one form or another of a pistol grip handle mechanism, along with a ratcheting or ratchetless device operatively associated with the handle for incrementally advancing the piston within the cylinder of the dispenser. The ratcheting device may be operated through a trigger member mounted adjacent the piston grip handle. Roller mechanisms, for instance, are more applicable for use with rather "stiff" collapsible containers and are not very effective for use with relatively "limp" containers because of jamming problems with the roller carriage, and the rollers are not effective when the extrudable material includes lumpy particles.
Although dispensers of the character described for extruding viscous contents from collapsible containers have been proposed for many years, there still is a definite need for a much more effective dispenser than has heretofore been available. This has become particularly prevalent in dispensing fluid condiments, such as ketchup, mustard, tartar sauce and the like, from collapsible containers in high volume restaurants or other establishments. These collapsible containers commonly are called "pouches" and the viscous material is contained in a relatively thin or limp plastic container versus the more stiff containers for products such as grease, toothpaste and the like. In addition, whereas the prior art is directed to dispensing extrudable material from tubularly shaped collapsible containers, such pouches are generally rectangularly shaped and generally flat in configuration, with heat sealed hems about the periphery thereof. It would be very difficult to manipulate and hold such pouches between the rollers of a roller-type dispenser. In addition, heretofore, it has been assumed that it would be very difficult, if not impossible, to use piston-type dispenser guns of the prior art for such applications. Still further, in high volume food establishments, it is desirable to ensure that a high percentage of the contents of the pouches are extruded when empty in order to avoid costly waste. And still further, in high volume food establishments, quality control is considered critical, whereby precise metered amounts of the condiments are required for dispensing onto a given food product according to very specific "recipe" parameters.
This invention is directed to satisfying the needs, to solving the problems and to overcoming the limitations of prior dispensing devices or systems as outlined above. The invention particularly is directed to a number of unique features in a dispenser of the character described.